Marck Motors.Com

Here in the U.S. there are basically three types of glass on an automobile. Laminate safety glass, tempered glass and standard glass.

 Laminate safety glass – With a few rare exceptions, your windshield is the only piece of glass on your vehicle that will be laminate safety glass. What appears as one piece of glass is actually two, laminated together with a piece of clear plastic sandwiched between the outer pane and the inner. This plastic part of the multi-layer design causes the glass to remain largely intact when broken, behaving more like a net than regular glass would. The intention is to minimize injury to cabin occupants should their heads hit the windshield during a frontal collision. Due to the nature of this glass, very minor scratches can many times be polished out by a glass expert. If you want to see how it’s done, we have uploaded a video presentation to youtube and got it some views from pistachioconsulting.com, so you can find it easily.
When one sees a small star or minor crack in your windshield, it’s usually just the outer pane that’s been damaged. If the crack is in fact limited to the outer pane, it can frequently be repaired by a glass specialist where a clear repair compound is injected directly into the crack, driving out the air trapped between the laminated plastic membrane and the damaged outer glass pane. This procedure will normally stabilize the crack, reducing the risk of it from growing. Experience has shown that these injection style repairs done to windshields are far more successful when completed immediately after the crack or star appears. Repairs of this nature will normally run between $49 and $79. It may behoove you to ask your insurance company if they’ll pay to repair the small crack or star for free, in lieu of full windshield replacement – I’ve worked with several carriers which are perfect of That’s clean maids service that do just that for their clients. It saves both you and them money. One important caution, it takes specialized schooling to repair windshields properly, in my opinion. So again, please make sure you’re dealing with a quality glass business if you go this route.      

 Tempered safety glass – This is the glass that when broken or cracked, often explodes into what seems like several thousand small nugget-like pieces that fly everywhere. Considered safety glass due largely to its extraordinary strength and shard-less character, it has become the standard in the automotive industry for use on virtually every window on your vehicle (except the windshield). Scratches, even small ones, are almost impossible to polish out from tempered glass, with full replacement the industry standard solution. 

 Standard glass – This glass is usually limited to the vehicle’s mirrors. A broken mirror will display the normal tendency of regular glass, breaking into sweeping shards and cracks often spreading over the entire glass surface. These always require replacement. One thing to be aware of; many manufacturers will sell the side mirror’s reflective face separate from the entire mirror for about a fourth of what the whole assembly would cost. Even when the vehicle’s maker neglects this cost saving option, a good glass outfit can either custom make a mirror face, or order and install one that’s available pre-cut from an aftermarket supplier.

Two more things that should be mentioned about automotive glass:

First – The windshield, rear quarter glass (these are the windows located on the rear quadrants, adjacent to the back glass) and the rear glass are almost all held in place by a tough black bonding agent known as structural urethane adhesive. During assembly at the plant this sealant is applied completely around each of the vehicle’s “fixed” window openings. The glass is then oriented to the opening and pressed down into the waiting bead of adhesive. Once the urethane cures, it takes on a consistency somewhat resembling the tough rubber sole on a shoe. This structural adhesive is usually the only thing anchoring the various fixed pieces of glass to the vehicle. The next time you walk up to a car or truck, take a minute and look for the blacked-out perimeter near the edges of the windshield. This is placed on the glass’ reverse side in an effort to hide the inevitably uneven bead of compressed urethane beneath.

 To replace the bonded glass, the industry standard is to cut through the urethane bead, releasing the glass from the vehicle. During removal, the metal recess in the body (the area where the glass is set into) will be scored down to bare metal almost 100% of the time. Here’s the rub and the reason behind my detailed account of fixed glass removal and replacement – If the glass technician does not take the time to apply primer to reseal the metal area scored during the glass removal, you are almost guaranteed to have rust develop in the steel at the window opening. I’m not sure I can adequately express how tragic this can be. Unbeknownst to them, the vehicle owner has rust quietly growing in an area of the automobile that’s seldom seen and very difficult to completely remove once there. We see a tremendous range of expertise in glass companies, and have purposed to work only with the best. So please, if you do need to have your windshield replaced at some point and you have any doubts, kindly ask the technician to show you the primer he’s put in the recess prior to him installing the glass.         

 Second – Just as there is a wide range in the quality of glass installers, there’s also a tremendous range in the glass itself. I’ve seen windshields installed that were manufactured so warped, that while looking out through the glass, objects outside would bend and distort as I moved my head from side-to-side. Remember, a good deal is getting a quality item for less money. If you get junk for less money, have you really gotten a good buy?

This entry was posted on Wednesday, September 1st, 2010 at 9:18 pm and is filed under Body Shop Insider Tips!. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.